When the oceanographer Charles Moore first discovered the Great Pacific Garbage Patch–an area of the ocean where currents concentrate the plastic we throw into the ocean–in 1997, he was shocked by its magnitude and persistence. “It seemed unbelievable, but I never found a clear spot,” he wrote later in Natural History magazine. “In the week it took to cross the subtropical high, no matter what time of day I looked, plastic debris was floating everywhere: bottles, bottle caps, wrappers, fragments.” In the years since the plastic buildup has only worsened. In a recent article in the New York Times, Moore reported that the Patch, through a process of accretion, now contains “solid areas you could walk on.”